Wearable monitoring and treatment device

ABSTRACT

A wearable medical device is provided. The wearable medical device includes a garment that includes a sensing electrode, at least one of an inductive element and a capacitive element included in at least part of the garment, and a controller. The controller may be configured to determine a confidence level of information received from the sensing electrode based on at least one of an inductance of the inductive element and a capacitance of the capacitive element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §120 to U.S.application Ser. No. 14/161,017, (now U.S. Pat. No. 9,131,901) titled“WEARABLE MONITORING AND TREATMENT DEVICE”, filed Jan. 22, 2014, whichclaims priority under 35 U.S.C. §120 to U.S. application Ser. No.13/598,380, (now U.S. Pat. No. 8,644,925) titled “WEARABLE MONITORINGAND TREATMENT DEVICE”, filed Aug. 29, 2012, which claims priority under35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/530,261titled “WEARABLE MONITORING AND TREATMENT DEVICE,” filed Sep. 1, 2011,and to U.S. Provisional Application Ser. No. 61/679,143 titled “WEARABLEMONITORING AND TREATMENT DEVICE,” filed Aug. 3, 2012, each of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

At least one embodiment of the present invention relates generally to awearable therapeutic device, and more specifically, to a wearabletherapeutic device configured to monitor or treat a subject.

2. Discussion of Related Art

Cardiac arrest and other health ailments are a major cause of deathworldwide. Various resuscitation efforts aim to maintain the body'scirculatory and respiratory systems during cardiac arrest in an attemptto save the life of the victim. The sooner these resuscitation effortsbegin, the better the victim's chances of survival. Health careprofessionals also attempt to detect and prevent conditions conducive tocardiac ailments by treating patients with drugs or by suggestinglifestyle changes. These efforts are expensive and have a limitedsuccess rate, and cardiac arrest, among other conditions, continues toclaim the lives of victims.

SUMMARY OF THE INVENTION

Aspects and embodiments of the present invention are directed to awearable therapeutic device that is configured to be worn by a subject.Electrodes sense information about the subject's health, and can applytreatment to the subject. At least one inductive or capacitive elementis included in a portion of the therapeutic device. Characteristics ofthe inductive or capacitive element, such as its radius or shape, changewhen the wearable therapeutic device expands, stretches, or otherwisechanges shape, which changes the inductance of the inductive element orthe capacitance of the capacitive element. Based at least in part onchanges in the inductance or the capacitance as the wearable therapeuticdevice changes shape, the wearable therapeutic device can providenotifications to the subject regarding arrhythmias, cardiac events, thecondition of the wearable therapeutic device, and the positioning ofelectrodes or other wearable therapeutic device components relative tothe subject.

At least one aspect is directed to a wearable therapeutic device. Thewearable therapeutic device includes a garment that is configured toinclude a sensing electrode. At least one of an inductive element and acapacitive element is included in at least part of the garment, and acontroller is configured to determine a confidence level of informationreceived from the sensing electrode based on at least one of aninductance of the inductive element and a capacitance of the capacitiveelement.

At least one other aspect is directed to a method of facilitating careof a subject. The method provides a wearable therapeutic deviceconfigured to include a sensing electrode, and receives, from thesensing electrode, information about the subject. The method alsodetermines inductance of an inductive element or capacitance of acapacitive element included in the wearable therapeutic device, anddetermines a confidence level of the information about the subject basedon the inductance or the capacitance.

At least one other aspect is directed to a non-transitory computerreadable medium having stored thereon sequences of instruction. Theinstructions include instructions that will cause a processor toreceive, from a sensing electrode of a wearable therapeutic device,information about a subject, and to determine inductance of an inductiveelement or capacitance of a capacitive element included in the wearabletherapeutic device. The instructions also cause the processor todetermine a confidence level of the information about the subject basedon the inductance or the capacitance.

In some embodiments, the wearable therapeutic device includes an alarmmodule coupled with the controller and configured to provide anotification to a subject based on the confidence level. In oneembodiment, the controller determines at least one of the inductance ofthe inductive element or the capacitance of the capacitive element.Based on the confidence level, in some embodiments a notification to thesubject is provided regarding at least one of a diagnosis andinformation about the wearable therapeutic device.

In various embodiments, a therapy electrode is included in the garment.The controller can determine information regarding positioning of thetherapy electrode or the sensing electrode based on the inductance ofthe inductive element or the capacitance of the capacitive element. Adefibrillator is coupled to the therapy electrode and together with thetherapy electrode can apply treatment to the subject, based on theconfidence level of the information received from the sensing electrode.The controller can identify, based on the inductance or the capacitance,an expansion of the garment, and can determine, based on the expansion,that positioning of at least one of the sensing electrode and thetherapy electrode is outside a tolerance range. In one embodiment, thecontroller can withhold treatment of the subject based on thepositioning of at least one of the sensing electrode and the therapyelectrode. The controller can determine, based on the expansion of thegarment, respiratory function of the subject. In one embodiment, thealarm module can provide instructions to the subject regardingpositioning of the sensing electrode or the therapy electrode based onthe expansion of the garment. The controller can determine a secondinductance value of the inductive element and can determine theconfidence level based on a differential between the first inductancevalue and the second inductance value. The controller can also determinea second capacitance value of the capacitive element and can determinethe confidence level based on a differential between the firstcapacitance value and the second capacitance value.

In some embodiments, a belt or a strap is configured to include at leastone of the inductive element and the capacitive element, and at leastone of the sensing electrode, the controller, the alarm module, atherapy electrode, and a defibrillator. In on embodiment in which thebelt or strap includes an inductive element, the belt can include acore, wherein the inductive element is coiled around the core. Thenotification can indicate that the garment is properly positioned aboutthe subject, too loose about the subject, too tight about the subject,soiled, or expired.

In some embodiments, the information received from the sensing electrodeincludes electrocardiograph information of the subject, and theconfidence level can be determined based on the expansion of the garmentand the electrocardiograph information of the subject. An arrhythmiccardiac event can be identified based on the confidence level,positioning of the therapy electrode can be verified, and the therapyelectrode can be instructed to apply treatment to the subject. Thecontroller can determine the confidence level based on theelectrocardiograph information of the subject. The controller can alsodetermine an absence of an arrhythmic cardiac event based on theinductance of the inductive element or the capacitance of the capacitiveelement and the electrocardiograph information of the subject.

In some embodiments, the wearable therapeutic device includes a therapyelectrode and a defibrillator. The positioning of the sensing electrodeor the therapy electrode can be verified based on the inductance of theinductive element or the capacitance of the capacitive element.Treatment can be applied to the subject using the therapy electrode andthe defibrillator. The inductive element or the capacitive element canbe included in a belt of the wearable therapeutic device, and anexpansion of a circumference of the belt can be identified based on theinductance of the inductive element or the capacitance of the capacitiveelement. The confidence level of the information about the subject canbe determined based on the expansion of the circumference of the belt.In one embodiment, the inductive element or the capacitive element is ina garment of the wearable therapeutic device, and an expansion of thegarment can be identified based on the inductance of the inductiveelement or the capacitance of the capacitive element. Instructions canbe provided to the subject regarding positioning of the sensingelectrode or the therapy electrode based on the expansion of thegarment.

In various embodiments, the diagnosis includes a diagnosis of anarrhythmic cardiac event. Electrocardiograph information of the subjectcan be sensed, and an expansion of a portion of the wearable therapeuticdevice that includes at least one of the inductive element and thecapacitive element can be identified. The confidence level can bedetermined based on the expansion of the portion of the wearabletherapeutic device and the electrocardiograph information of thesubject, and the arrhythmic cardiac event can be identified based on theconfidence level. An absence of an arrhythmic cardiac event can also bedetermined based on the confidence level.

In one embodiment, improper positioning of the sensing electrode or thetherapy electrode can be identified based on the expansion. An absenceof an arrhythmic cardiac event can be identified based on the improperpositioning of the sensing electrode. In one embodiment, treatment ofthe subject can be withheld based on the improper positioning of thesensing electrode or the therapy electrode.

In some embodiments, instructions to operate the wearable therapeuticdevice can be provided. In one embodiment, instructions can cause aprocessor to receive sensed electrocardiograph information of thesubject, and identify an expansion of a portion of the wearabletherapeutic device that includes the inductive element or the capacitiveelement. The instructions can cause the processor to determine theconfidence level based on the expansion of the portion of the wearabletherapeutic device and the electrocardiograph information of thesubject, and to identify an arrhythmic cardiac event based on theconfidence level. The instructions can cause the processor to controlthe therapy electrode of the wearable therapeutic device to applytreatment to the subject. In one embodiment, the instructions can causethe processor to determine an absence of an arrhythmic cardiac eventbased on the confidence level.

Other aspects and embodiments are discussed in detail below. Theforegoing information and the following detailed description includeillustrative examples of various aspects and embodiments, and areintended to provide an overview or framework for understanding thenature and character of the claimed aspects and embodiments. Thedrawings provide illustration and a further understanding of the variousaspects and embodiments, and are incorporated in and constitute a partof this specification. The drawings, together with the remainder of thespecification, serve to describe and explain the claimed aspects andembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a block diagram depicting a wearable therapeutic device inaccordance with an embodiment;

FIG. 2 is a schematic diagram depicting a wearable therapeutic device inaccordance with an embodiment;

FIG. 3A is a schematic diagram depicting a portion of a wearabletherapeutic device that includes an inductive element in an unstretchedposition in accordance with an embodiment;

FIG. 3B is a schematic diagram depicting a portion of a wearabletherapeutic device that includes a capacitive element in an unstretchedposition in accordance with an embodiment;

FIG. 4A is a schematic diagram depicting a portion of a wearabletherapeutic device that includes an inductive element in a stretchedposition in accordance with an embodiment;

FIG. 4B is a schematic diagram depicting a portion of a wearabletherapeutic device that includes a capacitive element in a stretchedposition in accordance with an embodiment;

FIG. 5 is a functional block diagram depicting a wearable therapeuticdevice controller in accordance with an embodiment;

FIG. 6 is a graph depicting tolerance stretch ranges of a wearabletherapeutic device in accordance with an embodiment; and

FIG. 7 is a flow chart depicting a method of facilitating care of asubject in accordance with an embodiment.

DETAILED DESCRIPTION

The systems and methods described herein are not limited in theirapplication to the details of construction and the arrangement ofcomponents set forth in the description or illustrated in the drawings.The systems and methods described herein are capable of otherembodiments and of being practiced or of being carried out in variousways. Also, the phraseology and terminology used herein is for thepurpose of description and should not be regarded as limiting. The useof “including” “comprising” “having” “containing” “involving” andvariations thereof herein, is meant to encompass the items listedthereafter, equivalents thereof, and additional items, as well asalternate embodiments consisting of the items listed thereafterexclusively.

Various aspects and embodiments are directed to a wearable therapeuticdevice. The wearable therapeutic device includes at least a sensingelectrode. An inductive or capacitive element is integrated into thewearable therapeutic device. Inductance of the inductive element orcapacitance of the capacitive element varies as these elements changeshape, for example due to stretching with use of the wearabletherapeutic device. A controller determines the inductance of theinductive element or capacitance of the capacitive element and togetherwith an alarm module or other interface or output, can provide anotification to the subject regarding, for example, the wearabletreatment device, a diagnosis, or a treatment regimen.

FIG. 1 is a block diagram of a wearable therapeutic device 100 inaccordance with an embodiment. In one embodiment, the wearabletherapeutic device 100 can be a wearable cardioverter defibrillator asdescribed in commonly owned U.S. patent application Ser. No. 13/109,079,titled “Wearable Therapeutic Device,” filed on May 17, 2011, which isincorporated by reference herein in its entirety.

Wearable therapeutic device 100 can include at least one garment 105 inthe shape of a vest or shirt. Garment 105 may also include at least onebelt 110. Belt 110 may be worn about a subject's waist, at a higherlocation about the subject's chest, or at other locations between thesubject's waist and shoulders. Components of wearable therapeutic device100, including garment 105, can be worn under, over, or partially underand partially over a subject's clothes.

In one embodiment, wearable therapeutic device 100 includes at least oneof the following elements: garment 105, belt 110, defibrillator 115,alarm module 120, monitor 125, controller 130, sensing electrode 135,therapy electrode 140, strap 145, inductive element 150, and capacitiveelement 155. In one embodiment, at least one of defibrillator 115, alarmmodule 120, monitor 125, controller 130, sensing electrode 135, therapyelectrode 140, inductive element 150, and capacitive element 155 areincluded in or attached to belt 110 or strap 145. For example, wearabletherapeutic device 100 components can be fitted into open or closedpockets of belt 110 or strap 145, or otherwise attached to theseelements via buckles, hook and loop fasteners, holsters, loops, orsleeves that form part of belt 110 or strap 145. These elements may alsobe integrated into belt 110 or strap 145, and these elements may be apermanent part of belt 110 or strap 145, or releasable from belt 110 orstrap 145. Garment 105 may include a series of belts 110 or straps 145,and need not constitute an article of clothing. Wearable therapeuticdevice 100 may include one, more than one, or all of the above mentionedelements, as well as additional elements such as at least one powersupply to provide power to controller 130, defibrillator 115, alarmmodule 120, monitor 125, sensing electrodes 135, or therapy electrodes140.

Defibrillator 115 can be included as part of wearable therapeutic device100. For example, defibrillator 115 can be included in garment 105,attached to strap 145, or disposed in belt 110. In one embodiment,defibrillator 115 is electrically coupled to therapy electrode 140.Defibrillator 115 can be an external defibrillator. Wearable therapeuticdevice 100 may include at least one receptacle having a conductive fluidencapsulated therein and housed in garment 105. For example, thereceptacle can be disposed in belt 110 or strap 145, proximate to atleast one of sensing electrode 135 and therapy electrode 140. In oneembodiment, electrodes 135 and 140 are dry electrodes. Controller 130 ordefibrillator 115 can release the conductive fluid from the receptaclesto enhance an electrical connection between sensing electrode 135 ortherapy electrode 140 and a subject wearing wearable therapeutic device100 to, for example, sense electrocardiograph information about thesubject or to apply treatment to the subject. The receptacles can bereplaced after their conductive fluid has been released, or upon theirexpiration. When a shock is applied, therapy electrodes 140, thesubject's body, and defibrillator 115 form at least part of a currentpath. One embodiment includes at least one sensing electrode 135, onetherapy electrode 140 disposed in front of the subject, e.g., proximateto the subject's chest, and two therapy electrodes 140 disposed in backof the subject, e.g. proximate to the subject's back.

Garment 105 can hold electrodes 135 and 140 in position, for exampleagainst the subject's skin around the subject's torso. Clothes or othermaterial may be present between garment 105 and the subject's skin. Whenpositioned against the subject, sensing electrodes 135 can senseelectrocardiogram signals used by controller 130 to monitor thesubject's cardiac activity. When controller 130 identifies an arrhythmiaor other cardiac event, therapy electrodes 140, when positioned againstthe subject can deliver defibrillating energy to the subject to convertthe arrhythmia to a normal sinus rhythm.

In one embodiment, sensing electrodes 135 and therapy electrodes 140 aresecurely positioned against the subject's body in order for sensingelectrodes 135 to sense cardiac, respiratory, or other information aboutthe subject; and for therapy electrodes 140 to apply treatment to thesubject. For example, sensing electrode 135 can includeelectrocardiogram electrodes that directly or indirectly (e.g., viaclothes, a conductive protective barrier, or a conductive fluid) contactthe subject's skin to sense an electrocardiogram signal with minimalartifacts. Further, therapy electrode 140 can directly or indirectlycontact the subject's skin to reduce impedance between therapy electrode140 and the subject's skin and to efficiently deliver defibrillatingenergy to the subject, without causing burns, blisters, inflammation, orother damage to the subject's skin. In one embodiment, conductive fluidis released from replaceable receptacles that are disposed in wearabletherapeutic device 100 to contact the subject's skin and surfaces ofsensing electrode 135 or therapy electrode 140 to reduce impedance andimprove the quality of sensed electrocardiogram signals.

In one embodiment, controller 130 includes at least one processor asdescribed in commonly owned U.S. patent application Ser. No. 12/833,096,titled “System and Method for Conserving Power in a Medical Device,”filed on Jul. 9, 2010 (hereinafter “the '096 application”), which isincorporated by reference herein in its entirety. The '096 applicationgenerally describes a processing architecture configured to conserveenergy and which may be used in a wearable therapeutic device, such as awearable defibrillator. Controller 130 can monitor a subject's conditionand control wearable therapeutic device 100 operations. For example,sensing electrode 135 can sense electrical activity of the subject'sheart signals, and controller 130 can provide these signals for displayas an electrocardiograph on monitor 125. When an arrhythmic event orother form of cardiac distress is detected, controller 130 can instructalarm module 120 to provide a warning that the subject wearing wearabletherapeutic device 100 is in danger of, or is experiencing, for example,cardiac arrest. Where the subject does not respond to the warning, thecontroller 130 can direct the defibrillator 115 to apply an electricshock to the body of the subject in an effort to restore a normalrhythm. Information concerning the subject's condition, such as thesubject's electrocardiogram (ECG), information relating to detectedarrhythmic events, information pertaining to any defibrillation shocksapplied to the subject, and other information can be stored in memoryunits associated with controller 130 for analysis by a doctor, rescuer,the subject, or a health care provider.

In one embodiment, the functionality of defibrillator 115 may beperformed at least partially in software executed by the at least oneprocessor of the controller 130 in a manner such as described in the'096 application. In other embodiments, the functionality ofdefibrillator 115 may be implemented in a Field Programmable Gate Array(FPGA), one or more Programmable Logic Devices (PLDs), a Complex PLD(CPLD), a custom Application Specific Integrated Circuit (ASIC), or adedicated processor operating under the control of the at least oneprocessor of the controller 130. It should be appreciated that otherimplementations may be used, as the present invention is not limited toany particular implementation.

In one embodiment, alarm module 120 provides an alarm or warning thatindicates that the subject will receive an electric shock fromdefibrillator 115 and at least one therapy electrode 140 when thesubject is wearing wearable therapeutic device 100, with therapyelectrode 140 disposed proximate to the subject's body. This alarm orwarning may be audio, visual, haptic (e.g., vibrating alarm module 120)or combinations thereof. Treatment in the form of an electric shock canbe applied to the subject wearing wearable therapeutic device 100 unlessthe subject takes some action to prevent defibrillator 115 from applyingthe shock. For example, alarm module 120 or monitor 125 may include aninterface having at least one button or touch screen. In this example,the subject can depress a button. This indicates that the subject isconscious. In this example, the shock will not be applied while thesubject depresses the button for a sufficient amount of time, or untilcontroller 130 determines that the electrical heart activity of thesubject, detected for example by sensing electrode 135, has returned tonormal. Continuing with this example, if the subject loosesconsciousness, the subject will release the buttons and defibrillator115 can apply a shock via at least one therapy electrode 140.

Alarm module 120 can be part of monitor 125 or a separate element ofwearable therapeutic device 100. In one embodiment, alarm module 120alerts and instructs the subject to take corrective action to repositionsensing electrode 135 or therapy electrode 140. For example, alarmmodule 120 can instruct the subject to tighten belt 110 to position orreposition sensing electrode 135 or therapy electrode 140. This canreduce, for example, signal interference at sensing electrode 135 bypositioning this electrode proximate to the subject's skin, or proximateto a desired portion of the subject's body where a strongerelectrocardiogram signal can be sensed. This can also reduce impedancebetween therapy electrode 140 and the subject, or between a plurality oftherapy electrodes 140, allowing for more efficient and effectiveapplication of therapy to the subject.

In one embodiment, at least one sensing electrode 135 and at least onetherapy electrode 140 are permanent components of wearable therapeuticdevice 100. Electrodes 135 and 140 can be housed anywhere in garment105. For example, at least one sensing electrode 135 can be integral togarment 105 and disposed proximate to the subject's chest or abdomenwhen the subject is wearing wearable therapeutic device 100. At leastone therapy electrode 140 can be integral to garment 105 and disposedproximate to the subject's back when the subject is wearing wearabletherapeutic device 100. Sensing electrode 135 and therapy electrode 140may include conductive surfaces such as a metal plate or foil in agenerally circular, ovoid, or quadrilateral shape.

In one embodiment, sensing electrode 135 and therapy electrode 140include conductive thread woven, sewn, or embroidered into wearabletreatment device 100. The conductive thread can provide connectionsbetween any of electrodes 135 and 140, and a battery powereddefibrillator 115. In one embodiment, sensing electrode 135 senses thesubject's electrocardiogram signals and provides that signal todefibrillator 115.

The conductive thread that may form at least part of sensing electrode135 and therapy electrode 140 can have various patterns to achieveproper electrocardiogram sensing and to administer therapy. In oneembodiment, sensing electrode 135 or therapy electrode 140 include onlyconductive stitching. Sensing electrode 135 or therapy electrode 140 mayalso include conductive stitching that holds a metal foil or otherconductive component in place in garment 105, so that sensing electrode135 or therapy electrode 140 includes both conductive thread and aconductive foil.

The conductive thread can be sewn into garment 105 (e.g., belt 110) in azigzag pattern that can stretch as part of garment 105. This stretchableconductive thread stitching connects sensing electrode 135 and therapyelectrode 140 with controller 130 or other garment 105 components (e.g.,defibrillator 115) in the absence of additional wires. In oneembodiment, the conductive thread (e.g., conductive wiring) can facetoward or away from the subject's skin.

In one embodiment, garment 105 includes breathable fabric, or a materialthat wicks heat away from the subject's body. This can reduce heatbuildup between the subject's skin and sensing electrode 135 or therapyelectrode 140. Using conductive thread for electrodes 135 or 140 reducesheat buildup in one embodiment when electrodes 135 or 140 are formedfrom conductive thread in the absence of any further metallic orconductive foil. In one embodiment, sensing electrode 135 or therapyelectrode 140 are made of perforated materials that allow air flowproximate to the subject's skin. This air flow can dry sweat or otherfluid from the skin to avoid rashes and other skin problems as a resultof heat buildup and irritation.

Garment 105 can be adjusted to snugly fit the subject. For example,portions of garment 105 that include sensing electrode 135 and therapyelectrode 140 can be substantially flush against the subject, e.g.,electrodes 135 and 140 remain substantially in a fixed position againstthe subject when the subject is moving about as part of a daily routine,or undertaking moderate physical activity. Clothing may be presentbetween garment 105 and the subject. Where clothing is present betweengarment 105 and the subject, the clothing preferably includes openingsto permit electrodes 135 to directly contact the subject's skin. Alarmmodule 120 can alert the subject when wearable therapeutic device 100 isnot sufficiently tight and snug about the subject. For example, alarmmodule 120 can notify the subject when the portion of garment 105 thatincludes sensing electrode 135 or therapy electrode 140 is not flushwith or fairly tightly pressed against the patient in a substantiallyfixed position.

Garment 105 or its components such as belt 110 or strap 145 may expandor stretch with time or repeated use, which can loosen the fit andpositioning of sensing electrode 135 and therapy electrode 140 proximateto the subject. Further, the subject's respiration will typically resultin periodic expansion of garment 105. Controller 130 can detect thisexpansion and where appropriate, instruct the subject to repositionsensing electrode 135 or therapy electrode 140, for example bytightening garment 105.

To identify garment 105 stretching, in one embodiment wearabletherapeutic device 100 includes at least one inductive element 150.Inductive element 150 includes a metallic or other conductive material,such as a conductive wire or thread that is configured in a coiledpattern (e.g., spring shaped) that includes a plurality of coils (e.g.,windings or turns) with a substantially similar radius. In oneembodiment, inductive element 150 includes at least one coiledconductive element that acts as an inductor when alternating current isapplied to it. In some embodiments, a magnetic core may be disposedwithin the plurality of coils.

In an alternate embodiment, inductive element 150 may be formed from aconductive wire or thread that is configured in a serpentine patternsimilar in shape to that shown in FIGS. 3B and 4B that includes aplurality of serpentine turns of similar dimension.

In another embodiment, wearable therapeutic device 100 includes at leastone capacitive element 155 to identify garment 105 stretching. In oneembodiment, the at least one capacitive element 155 can be formed from aconductive material such as a pair of wires with a round circumferenceor with at least one flat side, configured in parallel with each otherin a serpentine or coiled pattern in garment 105. A space may be presentbetween two capacitive elements 155, and may be occupied by aninsulator, dielectric material, or air so that the two capacitiveelements 155 act as a capacitor when supplied with power.

Inductive element 150 and capacitive element 155 may be shielded,jacketed, or insulated, and can connect to a power supply of wearabletherapeutic device 100. This power supply can also be associated withdefibrillator 115, controller 130, alarm module 120, or monitor 125. Inone embodiment, wearable therapeutic device 100 can include bothinductive element 150 and capacitive element 155.

Inductive element 150 and capacitive element 155 can stretch or expandtogether with garment 105. For example, inductive element 150 caninclude wire configured in a serpentine pattern or a wire configured ina coiled pattern whose radius and the number of turns or coils over adefined length change when stretched, which changes the inductance ofinductive element 150. When capacitive element 155 is stretched togetherwith garment 105, the capacitance changes, for example reducing whenstretched. In one embodiment, controller 130 detects the inductance ofinductive element 150 or capacitance of capacitive elements 155 todetermine if sensing electrode 135 or therapy electrode 140 is properlyor improperly positioned. For example, inductance or capacitance outsideof a tolerance range or above or below a threshold value can indicatethat sensing electrode 135 or therapy electrode 140 is improperlypositioned or tensioned due to garment 105 stretching, and inductance orcapacitance within a tolerance range or above or below a threshold valuecan indicate that no or minimal stretching of garment 105 has occurredand that electrodes 135 and 140 are properly positioned about thesubject.

In one embodiment, sensing electrodes 135 or therapy electrodes 140 areproperly positioned when they are adequately pressured by garment 105 tobe firmly pressed against the subject so that they are held in asubstantially fixed position to sense the subject's condition or delivertreatment. Properly positioned sensing electrodes 135 and therapyelectrodes 140 are generally held by garment 105 in a fixed positionwith minimal movement and in contact the subject's skin. Conductivefluid or other materials may be present between sensing electrodes 135or therapy electrodes 140 and the subject's skin.

Alarm module 120, which may include an interface and be part of monitor125, can indicate both proper and improper positioning of electrodes 135and 140, and can instruct the user to take corrective action, forexample when the determined inductance of inductive element 150 orcapacitance of capacitive element 155 indicates that stretching ofgarment 105 has displaced electrodes 135 or 140 so they are improperlypositioned.

FIG. 2 is a schematic diagram depicting subject 200 wearing wearabletherapeutic device 100 in accordance with an embodiment. In the exampleof FIG. 2, inductive element 150 is included in belt 110 and extendscircumferentially around subject 200, and capacitive element 155 isincluded in strap 145 in a tightly wrapped pattern configured to stretchwith strap 145. Other configurations are possible. For example,inductive element 150 can be included in strap 145 and capacitiveelement 155 can be included in belt 110. Further, inductive element 150and capacitive element 155 can extend across or be disposed in anyportion of garment 105, and need not be circumferential as illustratedin FIG. 2.

Wearable therapeutic device 100 can also include more than one inductiveelement 150 and more than one capacitive element 155, and need notinclude both types of elements. For example, a first inductive element150 or capacitive element 155 can be included in a portion of belt 110and a second inductive element 150 or capacitive element 155 can beincluded in a portion of strap 145 on one side of the subject, withoutextending around the subject. In one embodiment, a single inductiveelement 150 or capacitive element 155 is included in portions of bothbelt 110 and strap 145. Wearable therapeutic device 100 can includeother elements not illustrated in FIG. 2, such as additional strapsacross the chest of subject 200 that can include inductive element 150or capacitive element 155.

In one embodiment, controller 130 determines the inductance of inductiveelement 150, or the capacitance of capacitive element 155. Based on thedetermined inductance or capacitance, controller 130 can instruct alarmmodule 120 to provide a notification to subject 200. The notificationcan instruct subject 200 to loosen or tighten at least a portion ofgarment 105 (e.g., belt 110). The notification can also indicate that anarrhythmic cardiac event has been detected, based on information fromsensing electrode 135.

FIG. 3A depicts a portion of wearable therapeutic device 100 thatincludes inductive element 150 in an unstretched position, and FIG. 4Adepicts a portion of wearable therapeutic device 100 that includesinductive element 150 in a stretched position. In one embodiment,controller 130 can determine differences between the inductance ofinductive element 150 in the unstretched position of FIG. 3A and thestretched position of FIG. 4A. For example, wearable therapeutic device100 may have the unstretched configuration of FIG. 3A when it is notbeing worn by the subject, or if it is too large for the subject; andmay have the stretched configuration of FIG. 4A if it is too small forthe subject or is currently being worn by the subject.

FIG. 3B depicts a portion of wearable therapeutic device 100 thatincludes capacitive elements 155 in an unstretched position, and FIG. 4Bdepicts a portion of wearable therapeutic device 100 that includescapacitive elements 155 in a stretched position. An insulator, space,gap, or dielectric 160 may be present between the two capacitiveelements 155. In one embodiment, controller 130 can determinedifferences between the capacitance of capacitive element 155 in theunstretched position of FIG. 3B and the stretched position of FIG. 4B,as stretching or movement of garment 105 changes the relative capacitivesurface area and/or distance between capacitive elements 155. Electrodes135 and 140 can be either properly or improperly positioned about thesubject in the configurations of FIGS. 3A, 3B, 4A, and 4B. It should beappreciated that inductive element 150 may alternatively have aserpentine shape as shown in FIGS. 3B and 4B instead of the coiled shapeshown in FIGS. 3A and 4A.

Inductive element 150 and capacitive element 155 can include a wire orthread sewn into garment 105. In one embodiment, inductive element 150or capacitive elements 155 can expand and contract with garment 105, butotherwise substantially maintain their shape. Inductive element 150 andcan also be wrapped around a core included in belt 110, strap 145, orother portion of garment 105.

FIG. 5 depicts an example configuration of controller 130. In oneembodiment, interface 505 connects inductive element 150 or capacitiveelement 155 with detector 510 (e.g. a logic device or circuit) tomeasure the inductance of inductive element 150 or the capacitance ofcapacitive element 155. Stretch detector 515 determines if at least aportion of garment 105 has stretched based upon the measured inductanceor capacitance value. For example, controller 130 can determine theinductance or capacitance with garment 105 in an unstretched position ata baseline first time when wearable therapeutic device 100 is not beingworn; and in a stretched position at a second time when wearabletherapeutic device 100 is being worn. In one embodiment, comparatorcircuit 520 compares the unstretched baseline inductance or capacitancevalue with the stretched inductance or capacitance value to determinewhether or not garment 105 has expanded or stretched, or to determinerelative stretching between the baseline and stretched values. Based onthis comparison, controller 130 and alarm module 120 can alert thesubject to a number of conditions, such as garment 105 being too looseor too tight, that garment 105 is appropriately snug against the body ofthe subject, or that garment 105 is soiled and needs to be laundered torestore its elasticity, or that the garment should be replaced forexample, due to its age.

FIG. 6 is a graph depicting tolerance stretch ranges of wearabletherapeutic device 100 in accordance with an embodiment. In the exampleof FIG. 6, when worn by subject 200, wearable therapeutic device 100 canbe classified in under stretch range 605, tolerance range 610, or overstretch range 615. These classifications can change with time, andsubject 200 can adjust wearable therapeutic device 100 components suchas belt 110 to change the classification between these ranges.

Wearable therapeutic device 100 can be determined by controller 130 tobe in or under stretch range 605, (e.g., Point A), tolerance range 610(e.g., Point B), or over stretch range 615 (e.g., Point C). Understretch range 605 can indicate that wearable therapeutic device 100 istoo loose or not sufficiently expanded, so that sensing electrode 135 ortherapy electrode 140 is not in a substantially fixed position, or isnot tightly fitted against subject 200. When controller 130 determinesthat wearable therapeutic device 100 is in under stretch range 605 basedon the inductance of inductive element 150 or the capacitance ofcapacitive element 155, alarm module 120 can instruct subject 200 totake some action, such as to tighten belt 110 or straps 145, to laundergarment 105 to improve its elasticity, or to replace garment 105 with anew one or one of a smaller size. For example, when the amount ofstretching deteriorates from a baseline value over time, garment 105 maybe losing elasticity and can be laundered to reintroduce elasticity tomake garment 105 tighter fitting. When stretching deteriorates toorapidly between launderings from a baseline value, e.g., is belowminimum tolerance threshold 620 and is too loose, garment 105 may benearing end of life and be in need of replacement. When controller 130determines that wearable therapeutic device 100 is over expanded or inover stretch range 615, alarm module can instruct subject 200 to loosenbelt 110 or straps 145, or to replace garment 105 with a new one or oneof a larger size. In one embodiment, controller 130 prevents applicationof treatment from therapy electrode 140 when garment 105 is determinedto be in under stretch range 605 and/or over stretch range 615.Controller 130 can also disregard or give less weight to informationreceived from sensing electrode 135 when garment 105 is determined to bein under stretch range 605 or over stretch range 615 because thesepositions outside tolerance range 610 can indicate that sensingelectrode 135 is not properly positioned about subject 200.

In one embodiment, controller 130 can determine that garment 105 iswithin tolerance range 610 and thus properly fitted about subject 200with sensing electrode 135 or therapy electrode 140 properly and snuglypositioned with respect to subject 200. When controller 130 determinesor verifies that wearable therapeutic device 100 is within tolerancerange 610, controller 130 can evaluate information received from sensingelectrode 135 to determine that subject 200 is or is not in need oftherapy to treat, for example, an abnormal cardiac or respiratory event.Continuing with this example, controller 130 can direct therapyelectrode 140 and defibrillator 115 to apply treatment to subject 200.

In one embodiment, minimum tolerance threshold 620 and maximum tolerancethreshold 625 are the limits of tolerance range 610. Thresholds 620 and625 need not be linear as depicted in FIG. 6. In one embodiment,thresholds 620, 625 can change with time. For example, as wearabletherapeutic device 100 degrades or becomes worn with time, minimumtolerance threshold 620 can increase, indicating an increase intightening may be necessary to position sensing electrode 135 or therapyelectrode 140. Alternatively, where a significant amount of noise onsensing electrode 135 is detected at a particular stretch level, orwhere a number of fall-off flags have been detected, or both; controller130 may adjust the minimum tolerance threshold to this level of stretch.In this example, controller 130 includes auto-learn or adaptive featureswhere controller 130 adjusts tolerance thresholds 620 or 625, ortolerance range 610, based on sensed electrode positioning, electrodefall off events, the force applied by garment 105 onto the subject, orfeedback from the subject regarding observed conditions or the subject'scomfort level. Maximum tolerance threshold 625 can also increase overtime, as for example subject 200 becomes accustomed to wearabletherapeutic device 100 and is able to comfortably withstand a tighterfit. In one embodiment, garment 105 exerts 0.050 lb of force on thesubject's body at minimum tolerance threshold 620 and 1.70 lb of forceon the subject's body at maximum tolerance threshold 625.

The auto-learn features of controller 130 can associate a particularfitting or level of snugness of garment 105 about subject 200 with asubstantially noise or artifact free ECG signal measured by sensingelectrode 135. For example, controller 130 can identify an amount offorce exerted by garment 105 on subject 200 during sensing of a usableECG signal by sensing electrode 135. In this example, the amount offorce identified by controller 130 is based on the detected inductanceof inductive element 150 or the detected capacitance of capacitiveelement 155. Controller 130 in this example identifies a tolerance range610 that includes this detected amount of force. If controller 130detects that garment 105 is in under stretch range 605 (e.g., too loose)or over stretch range 615 (e.g., too tight), controller 130 can instructsubject 200 to tighten or loosen garment 105, for example via alarmmodule 120 or monitor 125, to bring the force level within that oftolerance range 610. In this example, controller 130 identifies andcontinuously adjusts a custom tolerance range 610 for an individualsubject 200 and a particular garment 105 based on the fit of thatgarment 105 that provides sufficient force for a substantially artifactfree ECG signal.

Thus, with the auto-learn feature, controller 130 can determine oradjust the range of tolerance range 610 based on the quality of ECGsignals sensed by sensing electrode 135. For example, the force exertedby garment 105 on subject 200 during sensing of a substantially noise orartifact free ECG can be evaluated by controller 130 to determine thescope of tolerance range 610, with the force associated with a qualityECG signal being within tolerance range 610. Controller 130 can adjustthis range with time, for example as subject 200 gains or loses weight,or as garment 105 wears and its elasticity characteristics change. Itshould be appreciated that the level of snugness associated with aquality ECG signal, and thus tolerance range 610, may vary from subjectto subject.

In one embodiment, when wearable therapeutic device is in tolerancerange 610, garment 105 has an acceptable range of stretching. In thisillustrative embodiment, controller 130 can determine that sensingelectrode 135 and therapy electrode 140 are in proper position aboutsubject 200. Based on changes in the inductance or capacitance caused bygarment 105 expansion, controller 130 can determine respirationinformation (e.g., rates and volumes) of subject 200. Sensing electrode135, which may include an accelerometer, can also sense thisinformation. Respiratory information can also be determined based on theinductance or capacitance, which may change as garment 105 expands orcontracts with respiration. In one embodiment, controller 130 evaluatesrespiration information and electrocardiogram information to detect anarrhythmia.

Ranges 605, 610, and 615, and thresholds 620 and 625 can be indicated asstretching distances of garment 105, belt 110, strap 145 or othercomponents, as well as changes in circumference, diameter, or radius ofthese components. These ranges and thresholds can be determined based oninductance values of inductive element 150 or on the capacitance valuesof capacitive element 155. They can be indicated with inductance values,capacitance values, or units of distance.

In one embodiment, controller 130 evaluates the inductance orcapacitance and determines that garment 105 stretching is withintolerance range 610. In this example, sensing electrodes 135 sensecardiac (e.g., electrocardiogram) information about subject 200.Respiratory information can also be sensed or deduced from changes ininductance or capacitance. In this example, the cardiac information canindicate that subject 200 is suffering an arrhythmia at the same timethe respiratory information indicates that subject 200 has stoppedbreathing. Because, in this example, garment 105 is within tolerancerange 610, controller 130 can determine with a high level of confidencethat sensing electrodes 135 are properly positioned. Based on thisconfidence level and the sensed information, controller 130 candetermine that the sensed information is accurate and that subject 200is experiencing an arrhythmia and in need of treatment. With garment 105within tolerance range 610, controller 130 can also determine with ahigh level of confidence that therapy electrode 140 is properlypositioned to apply an electric shock to subject 200 to treat thearrhythmia. In one embodiment, where an arrhythmia has been detected butcontroller 130 determines garment 105 is within tolerance range 610 andrespiratory information indicates normal breathing, controller 130 mayreduce the confidence level that the arrhythmia has been detected and/orthat the subject is in need of treatment.

Controller 130 can also determine that garment 105 is stretched outsideof tolerance range 610, (e.g., over or under stretched). In thisexample, respiration and cardiac information may be inconsistent witheach other due to movement or improper positioning with respect tosubject 200. Noise artifacts can further interfere with the sensedinformation. Continuing with this example, controller 130 can have a lowlevel of confidence that sensing electrodes 135 are properly positioned,(or a high level of confidence that they are improperly positioned).Based on this confidence level and the sensed information, controller130 can determine that the sensed information is inaccurate because thesensor is improperly positioned, and that subject 200 is notexperiencing an arrhythmia and does not need treatment. In this example,controller 130 can withhold, prevent, or block treatment from therapyelectrode 140 to subject 200 until controller 130 determines withsufficient confidence that information from sensing electrodes 135 isreliable and that sensing electrodes 135 and therapy electrode 140 areproperly positioned. Further, controller 130 can adjust the behavior ofwearable therapeutic device 100 based on the confidence level. Forexample, where the confidence level is low or decreasing with respect toa previous confidence level, controller 130 (and sensing electrodes 135)can sense ECG signals more frequently, or controller 130 can lengthen aresponse time during which the subject can respond to an alarmindicating a detected arrhythmia, or both.

Wearable therapeutic device 100 can identify arrhythmic cardiac eventsand apply treatment when garment 105 is in any range, including understretch range 605, tolerance range 610, and over stretch range 615. Forexample, while in tolerance range 610, controller 130 can identify anarrhythmia with less sensed information due to a high confidence levelthat the sensed information is accurate, and can direct therapyelectrodes 140 to apply treatment due to a high confidence level thatthey are properly positioned. While in ranges 605 or 615, controller 130may have a lower confidence level that the sensed information isaccurate and that electrodes 135, 140 are properly positioned. In thisexample, controller 130 may compensate for possible artifacts or flawsin the sensed information by evaluating sensed information over a longerperiod of time, or by evaluating information provided by additionalsensors 135 to identify an arrhythmia. Via alarm module, controller 130may prompt subject 200 for a response or ask the subject to indicatedistress, where an affirmative response or lack of any responseindicates that the subject is in need of treatment. In one embodiment,controller 130 may direct therapy electrode 140 to apply treatment evenwhen therapy electrode 140 is improperly positioned. The appliedtreatment may still be effective even though there may be a higherimpedance between therapy electrodes 140 and the subject's skin in thisexample.

In one embodiment, controller 130 determines different degrees ofconfidence that the sensed information is accurate and that electrodes135 and 140 are properly positioned. There can be two possibleconfidence levels (e.g., high/low, zero/one, yes/no) or confidencelevels can be provided as percentages (e.g., a 60% chance that thesensed information is accurate). Based on the confidence level,controller 130 can evaluate more or less sensed information, fromsensing electrode 135, inductive element 150, or capacitive element 155to provide a notification to the subject regarding positioning ofwearable therapeutic device 100, detection of an arrhythmia, orapplication of treatment. In one embodiment, suggestions or requirementsare provided to subject 200 to increase the confidence level, such assuggesting that subject 200 tighten garment 105 if subject 200 cantolerate the tightening, or indicate that sensors 135 and 140 arenonfunctional due to improper positioning and require their tighteningor replacement.

FIG. 7 is a flow chart depicting a method 700 of facilitating care of asubject. In one embodiment, method 700 includes an act of providing awearable therapeutic device (ACT 705). In one embodiment, providing thewearable therapeutic device (ACT 705) includes providing a device thatincludes a sensing electrode. The sensing electrode may be housed in agarment of the wearable therapeutic device, and providing the wearabletherapeutic device (ACT 705) may include providing a device with aninductive element or capacitive element included in at least part of thegarment. Providing the wearable therapeutic device (ACT 705) may alsoinclude providing a device having a controller configured to determineinductance of the inductive element or capacitance of the capacitiveelement, and to determine, based on the determined inductance orcapacitance, a confidence level of information received from the sensingelectrode. This information may include electrocardiograph or otherinformation about the subject's body functions. Providing the wearabletherapeutic device (ACT 705) may also include providing a device with analarm module coupled with a controller to notify the subject of events,conditions, or information about the subject's condition or about thecondition of the wearable therapeutic device, based on the confidencelevel of the information received from the sensor and the determinedinductance of the inductive element.

In one embodiment, method 700 includes an act of providing instructions(ACT 710). For example, providing instructions (ACT 710) can includeproviding instructions to operate the wearable therapeutic device, orproviding instructions on how to wear the wearable therapeutic device.In one embodiment, the instructions include instructions to the subjectregarding positioning of wearable therapeutic device components, such assensing or therapy electrodes. For example, instructions can be provided(ACT 710) to the subject, based on an expansion of the wearabletherapeutic device or its components, to position an electrode proximateto an area of the subject's body, such as the center of the back, orproximate to the chest and heart of the subject, so that the electrodesare positioned to provide therapy to the subject or sense cardiac orrespiratory function of the subject.

In one embodiment, method 700 includes an act of receiving informationabout the subject (ACT 715). In one embodiment, this information isreceived (ACT 715) from at least one sensing electrode. For example,receiving information (ACT 715) may include receiving sensedelectrocardiograph information of the subject. In this example, thereceived information includes information from a sensing electrode thatis part of the wearable therapeutic device and that can detectelectrocardiograph signals from a subject wearing the device. Thereceived (ACT 715) information can include cardiac, pulse, circulatory,respiratory, or pulmonary information of the subject. In one embodiment,receiving information (ACT 715) includes receiving information about theinductance of an inductive element or capacitance of a capacitiveelement disposed in part of the wearable therapeutic device. Theinductance value, capacitance value or changes in these values with timecan indicate that the wearable therapeutic device is in a stretched,expanded, or unexpanded position.

Method 700 also includes an act of determining inductance of aninductive element included in the wearable therapeutic device (ACT 720).In one embodiment, inductance is determined (ACT 720) with a sensor thatis part of the wearable therapeutic device that measures the inductance,or a logic device associated with the controller calculates inductancebased, for example, on the radius, number of turns, or length of thecoils of the inductive element disposed in the wearable therapeuticdevice.

Method 700 alternatively or additionally includes an act of determiningcapacitance of a capacitive element included in the wearable therapeuticdevice (ACT 723). In one embodiment, capacitance is determined (ACT 723)with a sensor that is part of the wearable therapeutic device thatmeasures the capacitance, or a logic device associated with thecontroller calculates capacitance of the capacitive element.

In one embodiment, method 700 includes an act of determining aconfidence level (ACT 725) of the received (ACT 715) information aboutthe subject. The confidence level may be determined (ACT 725) based onchanges in the inductance or capacitance with respect to a baseline orthreshold value. In one embodiment, the confidence level is determinedbased on identified expansion or stretching of a portion of the wearabletherapeutic device or any of its components. For example, the confidencelevel can be determined based on the expansion of the inductive elementor capacitive element, a belt or other portion of the wearabletherapeutic device that includes either of these elements, or acircumference of the wearable therapeutic device, its belt, strap, orgarment. In one embodiment, the confidence level is determined based onan expansion of a portion of the wearable therapeutic device thatincludes the inductive element or capacitive element and receivedinformation (ACT 715) about the subject that includes electrocardiographinformation.

Determining the confidence level (ACT 725) may include determining thatthe received information about the subject is accurate. For example, thedetermined inductance (ACT 720) or capacitance (ACT 723) can indicatethat the wearable therapeutic device has not stretched, or has stretchedless than a threshold amount, or within a defined acceptable parameteror range. In this example, the confidence level of the accuracy of thesensed information about the subject can be determined (ACT 725) to behigh, e.g., the sensed electrocardiograph or other information about thesubject can be accepted as valid information about the subject's healthand used as a factor in diagnosing the subject, e.g., by identifying anarrhythmic cardiac event, or applying treatment to the subject.

Determining the confidence level (ACT 725) may include determining thatthe received information about the subject is not accurate. In thisexample, the determined inductance (ACT 720) or capacitance (ACT 723)can indicate that the wearable therapeutic device has stretched to adegree that the sensing electrode that senses the received (ACT 715)information about the subject may have shifted about the subject to adegree where it is no longer properly positioned to sense, for example,a quality electrocardiogram signal. In this example, the confidencelevel in the accuracy of the sensed information can be low, and thesensed information may be disregarded or require further verification.

In one embodiment, method 700 includes an act of providing anotification to the subject (ACT 730) based on the confidence level. Thenotification may be audibly, visually, or haptically (e.g., a vibratingalarm) provided (ACT 730) to the subject. The notification may also beprovided (ACT 730) to another person such as the subject's doctor,family member, friend, or health care provider, who may be proximate tothe subject or at a remote location, e.g., via a transmission over anetwork. In one embodiment, the notification is provided to the subject(ACT 730) by an alarm module, monitor, or interface that is part of thewearable therapeutic device.

Providing the notification (ACT 730) may include providing a diagnosisof an arrhythmic cardiac event, fibrillation, cardiac arrest, abnormalrespiratory activity, or other condition that may require medicalattention. The provided notification (ACT 730) can indicate that thesubject has no immediate health issue requiring treatment, e.g., anormal cardiac rhythm or normal pulmonary activity. Providing thenotification (ACT 730) can also include providing information unrelatedto the subject's health, such as information about the use orpositioning of the wearable therapeutic device. For example, informationcan be provided (ACT 730) indicating that the sensing or therapyelectrodes of the wearable therapeutic device are not properlypositioned with respect to the subject wearing the device. This may bedue to stretching of the wearable therapeutic device with time and use.This stretching can cause the electrodes to shift position to a locationwhere they are less effective or ineffective to sense information aboutthe subject or apply treatment to the subject.

In one embodiment, method 700 includes an act of verifying positioningof wearable therapeutic device components (ACT 735), such as sensing ortherapy electrodes. For example, the position of wearable therapeuticdevice components can be verified (ACT 735) when the identifiedinductance (ACT 720) or capacitance (ACT 723) is analyzed to determinethat the amount of stretching of the wearable therapeutic device is lessthan a threshold amount, or within a tolerance range. This minimalstretching can indicate a tolerable level of displacement of wearabletherapeutic device components. Method 700 may also include an act ofapplying treatment to the subject (ACT 740). In one embodiment, applyingtreatment to the subject (ACT 740) includes delivering an electric shockto the subject from therapy electrodes that are included in the wearabletherapeutic device and an associated defibrillator.

Method 700 can also include an act of identifying improper positioningof wearable therapeutic device components (ACT 745). For example,improper positioning of wearable therapeutic device components can beidentified (ACT 745) when the identified inductance (ACT 720) orcapacitance (ACT 723) is analyzed to determine that the amount ofstretching of the wearable therapeutic device is more than a thresholdamount, or outside a tolerance range. This stretching can indicate anunacceptable level of displacement of wearable therapeutic devicecomponents during use of the wearable therapeutic device. Method 700 mayalso include an act of withholding treatment from the subject (ACT 750).In one embodiment, withholding treatment from the subject (ACT 740)includes delaying delivery an electric shock to the subject from therapyelectrodes that are included in the wearable therapeutic device and anassociated defibrillator until the therapy electrodes are moved to anappropriate location proximate to the subject, and until theirpositioning is verified (ACT 735). Withholding treatment from thesubject (ACT 750) can also include delaying delivery of an electricshock to the subject until sensing electrodes are moved to anappropriate location proximate the subject so that they can senseinformation at a confidence level sufficient to rely on for diagnosingthe subject's condition.

Having now described some illustrative embodiments, it is apparent thatthe foregoing is illustrative and not limiting, having been presented byway of example.

In particular, although many of the examples presented herein involvespecific combinations of method acts or system elements, it isunderstood that those acts and those elements may be combined in otherways. Acts, elements and features discussed only in connection with oneembodiment are not intended to be excluded from a similar role in otherembodiments.

Note that in FIGS. 1 through 7, the enumerated items are shown asindividual elements. In actual implementations of the systems andmethods described herein, however, they may be inseparable components ofother electronic devices such as a digital computer. Thus, actionsdescribed above may be implemented at least in part in software that maybe embodied in an article of manufacture that includes a program storagemedium. The software may be executed by a processor of controller 130.In one embodiment, the program storage medium is non-transient. Theprogram storage medium includes data signals embodied in one or more ofa carrier wave, a computer disk (magnetic, or optical (e.g., CD or DVD,or both)), non-volatile memory, tape, a system memory, and a computerhard drive.

Any references to embodiments or elements or acts of the systems andmethods herein referred to in the singular may also embrace embodimentsincluding a plurality of these elements, and any references in plural toany embodiment or element or act herein may also embrace embodimentsincluding only a single element. References in the singular or pluralform are not intended to limit the presently disclosed systems ormethods, their components, acts, or elements to single or pluralconfigurations. References to any act or element being based on anyinformation, act or element may include embodiments where the act orelement is based at least in part on any information, act, or element.

Any embodiment disclosed herein may be combined with any otherembodiment, and references to “an embodiment,” “some embodiments,” “analternate embodiment,” “various embodiments,” “one embodiment” or thelike are not necessarily mutually exclusive and are intended to indicatethat a particular feature, structure, or characteristic described inconnection with the embodiment may be included in at least oneembodiment. Such terms as used herein are not necessarily all referringto the same embodiment. Any embodiment may be combined with any otherembodiment in any manner consistent with the aspects and embodimentsdisclosed herein.

References to “or” should be construed as inclusive so that any termsdescribed using “or” may indicate any of a single, more than one, andall of the described terms. Intervening embodiments, acts, or elementsare not essential unless recited as such.

Where technical features in the drawings, detailed description or anyclaim are followed by reference signs, the reference signs have beenincluded for the sole purpose of increasing the intelligibility of thedrawings, detailed description, and claims. Accordingly, neither thereference signs nor their absence have any limiting effect on the scopeof any claim elements.

One skilled in the art will realize the systems and methods describedherein may be embodied in other specific forms without departing fromthe characteristics thereof. For example, the subject may be a patientand the wearable therapeutic device can store and transmit dataconcerning the patient's medical condition to a physician. Because thewearable therapeutic device can operate essentially at all times, thisdata can be used to generate a comprehensive real time record of thesubject's health over an extended period of time. The foregoingembodiments are illustrative rather than limiting of the describedsystems and methods. Scope of the systems and methods described hereinis thus indicated by the appended claims, rather than the foregoingdescription, and changes that come within the meaning and range ofequivalency of the claims are embraced therein.

What is claimed is:
 1. A wearable medical device, comprising: a garmentworn by a subject, the garment comprising one or more electrocardiographsensing electrodes configured to receive electrocardiograph informationfrom the subject; at least one of an inductive element and a capacitiveelement included in at least part of the garment; and a controllerconfigured to determine a confidence level of the electrocardiographinformation received from the one or more electrocardiograph sensingelectrodes based on at least one of a change in an inductance of theinductive element and a change in a capacitance of the capacitiveelement, the confidence level indicating whether the one or moreelectrocardiograph sensing electrodes are properly positioned on thesubject.
 2. The wearable medical device of claim 1, further comprisingan alarm module coupled to the controller and configured to provide anotification to the subject based on the confidence level.
 3. Thewearable medical device of claim 2, wherein the notification indicatesthat the garment is one of: properly positioned about the subject, tooloose about the subject, and too tight about the subject.
 4. Thewearable medical device of claim 1, wherein the controller is furtherconfigured to identify, based on the at least one of the change in theinductance of the inductive element and the change in the capacitance ofthe capacitive element, at least one of: expansion of the garment,tightening of the garment, improper positioning of the garment, andshifting of the garment.
 5. The wearable medical device of claim 4,further comprising a therapy electrode included in the garment andwherein the controller is further configured to determine, based on theat least one of the expansion of the garment, the tightening of thegarment, the improper positioning of the garment, and the shifting ofthe garment, that positioning of at least one of the one or moreelectrocardiograph sensing electrodes and the therapy electrode isoutside a tolerance range and to withhold treatment of the subject bythe therapy electrode based on the positioning of the at least one ofthe one or more electrocardiograph sensing electrodes and the therapyelectrode.
 6. The wearable medical device of claim 5, further comprisingan alarm module configured to provide instructions to the subjectregarding positioning of at least one of the one or moreelectrocardiograph sensing electrodes and the therapy electrode based onthe at least one of: the expansion of the garment, the tightening of thegarment, the improper positioning of the garment, and the shifting ofthe garment.
 7. The wearable medical device of claim 1, wherein thecontroller is further configured to identify an expansion of the garmentbased on the at least one of the change in the inductance of theinductive element and the change in the capacitance of the capacitiveelement and to determine respiratory function of the subject based onthe expansion of the garment.
 8. The wearable medical device of claim 1,further comprising a therapy electrode included in the garment, whereinthe confidence level further indicates whether the therapy electrode isproperly positioned on the subject, and wherein the controller isfurther configured to identify an arrhythmic cardiac event, verifypositioning of the therapy electrode included in the garment based onthe confidence level, and cause the therapy electrode to apply treatmentto the subject.
 9. The wearable medical device of claim 1, wherein thegarment comprises at least one of a belt and a strap configured toinclude the at least one of the capacitive element and the inductiveelement, and at least one of: the one or more electrocardiograph sensingelectrodes, the controller, an alarm module, a therapy electrode, and adefibrillator.
 10. The wearable medical device of claim 1, wherein thewearable medical device includes both the inductive element and thecapacitive element, and wherein the controller is configured todetermine the confidence level of information received from the one ormore electrocardiograph sensing electrodes based on both the change inthe inductance of the inductive element and the capacitance of thecapacitive element.
 11. The wearable medical device of claim 1, whereinthe controller is further configured to determine the confidence levelat least in part by determining that the one or more electrocardiographsensing electrodes is properly positioned on the subject based on the atleast one of the change in the inductance of the inductive element andthe change in the capacitance of the capacitive element.
 12. Thewearable medical device of claim 1, wherein the one or moreelectrocardiograph sensing electrodes senses electrocardiographinformation of the subject, and wherein the controller is furtherconfigured to determine the confidence level based on theelectrocardiograph information of the subject and the at least one ofthe change in the inductance of the inductive element and the change inthe capacitance of the capacitive element.
 13. The wearable medicaldevice of claim 1, wherein the controller is further configured todetermine an absence of an arrhythmic cardiac event based on theelectrocardiograph information of the subject and the at least one ofthe change in the inductance of the inductive element and the change inthe capacitance of the capacitive element.
 14. The wearable medicaldevice of claim 1, wherein the wearable medical device is a wearabletherapeutic device.